【正文】 soft Data Access Components (MDAC) have a different user interface for Client Network Utility. Therefore, if you do not see the 大連交通大學(xué) 2020屆本科生畢業(yè)設(shè)計(jì)（論文）外文翻譯 4 options that are listed in this article, install a later version of MDAC on the puter that is running the client application. Verify that the instance of SQL Server is listening correctly To verify that the instance of SQL Server is listening on named pipes, TCP/IP, or another protocol that you are using at the client application, open the current SQL Server error log file. The SQL Server error log file may contain entries that are similar to the following: 20201106 09:49: server SQL server listening on TCP, Shared Memory, Named Pipes. 20201106 09:49: server SQL server listening on :1433, :1433. If you analyze the entries in the SQL Server error log file, you can verify that the instance of SQL Server is listening on the correct IP address and on the correct port. By default, a default instance of SQL Server listens on the port 1433. You can also use Server Network Utility to verify the protocol settings for SQL Server and to change the properties in SQL Server, including the protocols that can connect to SQL Server and the ports that can be used. For more information about using Server Network Utility, see the SQL Server Network Utility topic in SQL Server Books Online. Sometimes, SQL Server 2020 may not bind to port 1433 or any other specified port. This problem may occur if the port is being used by another application or if you are trying to connect by using an IP address that is not correct. Therefore, the TCP/IP connections to SQL Server may not be successful and you may receive the following error message in the SQL Server error log file: 20201114 15:49: server SuperSocket Info: Bind failed on TCP port 1433. If you cannot connect to the instance of SQL Server by using a TCP/IP connection, try to use the named pipes protocol or the Shared Memory protocol. Run the following mand at a mand prompt to obtain information about the ports that are in use: NETSTAT –an You can also use the Portqry mandline utility to obtain more information about the ports that are in use. Note For named instances of SQL Server, SQL Server dynamically determines the port and listens on the determined port. Therefore, when you start the named instance of SQL Server, SQL Server tries to listen on the port that was previously being used. 大連交通大學(xué) 2020屆本科生畢業(yè)設(shè)計(jì)（論文）外文翻譯 5 If SQL Server cannot bind to that port, the named instance may dynamically bind to a different port. In that situation, make sure that the client application is also set to determine the port dynamically. Alternatively, you can also specify a static port for the named instance to bind to and to listen on by using Client Network Utility. Troubleshoot MDAC Issues Connectivity problems may also occur because of problems with MDAC. For example, a software installation may overwrite some of the MDAC files or change the permissions that you must have to access the MDAC files. You can run the MDAC Component Checker to verify the MDAC installation on your puter. Note If you are connecting to a named instance of SQL Server, make sure that you are running MDAC or later on your puter. Earlier versions of MDAC do not recognize named instances of SQL Server. Therefore, connections to named instances may not be successful. You can use the utility to verify connections through the SQL Server ODBC driver. You can also test connectivity to the instance of SQL Server by using a .udl file. Troubleshoot firewall issues If firewall exists between the client puter and the puter that is running SQL Server, make sure that the ports that are required to municate through the firewall are open. If you use the TCP/IP protocol to connect to the instance of SQL Server, make sure that you can use the Tel program to connect to the port where SQL Server is listening. To use the Tel program, run the following mand at a mand prompt: Tel IP Address Port Number If the Tel program is not successful and you receive an error message, resolve the error and then try to connect again. Note Because of issues that were caused by the Slammer virus, the User Datagram Protocol (UDP) port 1434 may be blocked on your firewall. Troubleshoot authentication and security issues Connections to SQL Server may not be successful because of authentication failures. If the authentication fails, you may receive one of the following error messages: 大連交通大學(xué) 2020屆本科生畢業(yè)設(shè)計(jì)（論文）外文翻譯 6 Login failed for user 39。username39。 Login failed for user 39。NTAUTHORITY\ANONYMOUS LOGON39。 Login failed for user 39。null39。 If you receive an error message because of an authentication failure and the error message does not mention a specific SQL Server login name, troubleshoot the problem with Windows authentication. You may receive the following error message because of problems with Windows authentication: Cannot generate SSPI Context The following problems may cause authentication and security issues: ? Problems occur with NTLM authentication or with Kerberos authentication. ? The domain controller cannot be contacted because of connectivity issues. ? Problems occur with trust relationships across domains. For more information about possible causes, see the event logs on the puter. To work around connectivity problems with Windows authentication, you can use SQL Server Authentication to connect to the instance of SQL Server. If the connection is not successful when you use SQL Server Authentication, you receive the following error message: Login failed for user 39。username39。 . Not associated with a trusted connection To troubleshoot this problem, follow these steps. Warning If you use Registry Editor incorrectly, you may cause serious problems that may require yo